Parcel singulation software control logic

ABSTRACT

A method and an apparatus are provided for singulating articles received in a slug and/or manipulating such articles to create a controlled gap between a trailing edge of a leading article and a leading edge of a successive article, while targeting a desired throughput. For singulation, a plurality of belts are mounted adjacent to each other with a slide chute between each pair of adjacent belts, articles moving from an infeed belt and passing from one belt to another through the chute therebetween. A plurality of sensors are positioned such that there is a single control sensor for at least selected ones of the belts, each control sensor sensing article position on a corresponding belt. Controls are provided for operating each belt in response to a corresponding control sensor, an operative state of a downstream belt and/or a difference between the desired throughput and detected throughput. For creating controlled gaps between successive articles, a plurality of belts are provided, mounted adjacent each other, articles being received on a first of the belts and passing from one belt to an adjacent belt. A plurality of control sensors are sensing article position relative to each belt and controls are provided which operate each belt in response to a corresponding control sensor, an operative state of a downstream belt and/or the difference between the desired throughput and the detected throughput. The controls are also operative to initiate stopping of a belt if a detected trailing-edge to leading-edge gap is smaller than the desired minimum gap.

FIELD OF INVENTION

[0001] This invention relates to article handling systems, and, moreparticularly, to a method and apparatus for singulating articles andestablishing a controlled inter-article gap.

BACKGROUND OF THE INVENTION

[0002] In mail processing, airport baggage claim service, assembly lineoperations and other applications involving transport and processing ofvarious articles, it is often necessary to separate articles randomlyreceived, sometimes enmass as a slug, stack or pile, into a stream ofsuccessive articles. This process of separating articles is generallyreferred to as “singulation”. In a post office or delivery service, forexample, packages may arrive at a conveyor system in randomly occurringslugs, the packages in each slug varying significantly in quantity, sizeand shape within allowed ranges. Singulating such packages or otherarticles is an essential preliminary step in performing sortation ormost other operations on such articles. For the articles to be sorted orotherwise processed, they also must, in most cases, be separated by agap of sufficient length. However, while at least a minimum gap betweensucceeding articles is required, spacing larger than the requiredminimum gap decreases throughput.

[0003] Automation apparatus is normally employed for article singulationand establishing proper article separations, such prior art apparatususing belt and chute systems, cameras and/or arrays of photo sensors foreach belt to determine positioning of articles on the belts, andmechanisms ranging from robotic arms, to mechanical guides, tocomplicated control logic for slowing down and speeding up the belts inorder to separate the articles to achieve singulation. Gapping apparatusinvolve various sensors for determining existing leading-edge toleading-edge or trailing-edge to leading-edge distance; gaps areadjusted to desired sizes via mechanical means.

[0004] While, combined, a singulation and a gapping apparatus wouldaccomplish the task of singulating and gapping articles, such apparatushas heretofore been expensive and hard to operate, requiring the use ofsophisticated technology. There exists a need for an apparatus that iscapable of achieving either one or both goals without the use ofcameras, computers to analyze digital images, or other expensiveequipment.

SUMMARY OF THE INVENTION

[0005] In accordance with the above, this invention provides a methodand an apparatus for singulating articles received in a slug and/ormanipulating such articles, particularly articles of various size, tocreate a controlled gap between the trailing-edge of a leading articleand a leading-edge of a successive article. For singulation, a pluralityof belts are provided, mounted adjacent to each other, with a slidechute between each pair of adjacent belts, articles being received on afirst of the belts and passing from one belt to an adjacent belt throughthe chute therebetween. A plurality of sensors are positioned such thatthere is a single control sensor for at least selected ones of thebelts, each control sensor sensing article position relative to acorresponding belt. Controls are provided for operating each belt inresponse to a corresponding control sensor and an operative state of adownstream belt.

[0006] The control sensor may be located at an end of a correspondingbelt, for example, the exit end of the corresponding belt. The controlsmay be operative to initiate stopping of a belt if a downstream belt isnot running and a corresponding control sensor has been blocked for aconfigurable period of time. Similarly, the controls are operative tostart or re-start a belt when the downstream belt is running. Forpreferred embodiments, the configurable time period is such that thebelt has not completely stopped when a run signal is sent. Theconfigurable time period may also be adjustable to achieve a desiredapparatus throughput, such adjustment, for example, being according toan adjustment schedule. The controls may, for example, include at leastone subroutine for each belt which is run on an appropriate processor.

[0007] The invention also includes apparatus for receiving articles in astream and creating a controlled gap between a trailing-edge of aleading article and a leading-edge of a successive article. Thisapparatus includes a plurality of belts mounted adjacent each other,articles being received on a first of the belts and passing from onebelt to an adjacent belt. A plurality of control sensors are positionedsuch that there is a single control sensor sensing article positionrelative to each belt and controls are provided which operate each beltin response to a corresponding control sensor and an operative state ofa downstream belt. The control sensor may be located at an end of acorresponding belt, for example, the exit end of such belt.

[0008] The plurality of belts may be logically divided into a firstsection which minimizes a gap time and a second section whichestablishes at least a minimum gap time between successive articles. Thecontrols are operative to initiate stopping of a belt in the firstsection if a downstream belt is not running and a corresponding controlsensor is blocked and to send a run signal when the downstream belt isrunning again. The controls are also operative to initiate stopping of abelt in the second section if a detected trailing-edge to leading-edgegap time is smaller than the desired minimum gap time, and a run signalis sent to the belt after a calculated time period, the calculated timeperiod being a function of a difference between the detected gap timeand the minimum gap time. More specifically, calculation of the abovefunction includes: (a) setting the calculated time period to be equal tothe difference between the detected gap time and the minimum gap time ifthe difference is larger than a determined fraction of the minimum gaptime; and (b) setting the calculated time period to be equal to afraction of the minimum gap time if the difference between the detectedgap time and the minimum gap time is smaller or equal to a determinedfraction of the minimum gap time. The controls are also operative toinitiate stopping of a belt, or at least a subset of the plurality ofbelts, if a corresponding control sensor has been blocked for more thana predetermined time period, which time period may be adjusted to targetthe desired throughput. For some embodiments, the predetermined timeperiod is smaller than, or at most equal to a time it would take for alongest article to move past the corresponding control sensor. Thecontrols preferably consist of at least one subroutine for each belt.

[0009] The invention further includes a method usable with an apparatusfor manipulating articles of various size which includes stages of beltscarrying the articles and belt controls for stopping and starting thebelts, the method maintaining a desired article throughput and includingthe steps of: (a) monitoring throughput for the article manipulation;and (b) controlling stop time intervals for at least selected ones ofthe belts to maintain the desired throughput. The step of controllingstop time intervals, step (b) above, may include: (c) adjusting at leastselected stop time intervals upward by a selected amount if currentthroughput is greater than the desired throughput; and (d) adjusting atleast selected stop time intervals downward by selected amounts ifcurrent throughput is less than the desired throughput. The stop timeintervals in steps (c) and (d) above may be adjusted according to atleast one adjustment schedule which adjustment schedule is stored in acomputer on which control subroutines are run.

[0010] The invention further includes apparatus for manipulatingarticles while maintaining a desired throughput, which apparatusincludes stages of belts carrying the articles, and controls operatingeach belt, the controls being operative to stop and start the belts, andincluding subroutines for monitoring throughput for the articlemanipulation and for controlling stop time intervals for at leastselected ones of the belts to maintain the desired throughput. Thesubroutines for controlling stop time intervals may include (a) asubroutine for adjusting at least selected intervals upward by aselected amount if current throughput is larger than the desiredthroughput; and (b) a subroutine for adjusting at least selectedintervals downward by a selected amount if current throughput is smallerthan the desired throughput. The adjustments by subroutines (a) and (b)above may be according to an adjustment schedule.

[0011] The foregoing and other objects, features and advantages of theinvention will be apparent from the following more particulardescription of a preferred embodiment of the invention as illustrated inthe accompanying drawings, the same reference numerals being used forcommon elements in the various figures.

[0012] Finally, the invention includes apparatus for receiving articlesin a slug, singulating the articles and creating a controlled gapbetween a trailing-edge of a leading article and a leading-edge of asuccessive article. This apparatus includes a plurality of belts mountedadjacent each other, articles being received on a first of the belts andpassing from one belt to an adjacent belt. A plurality of controlsensors are positioned such that there is a single control sensorsensing article position relative to each belt and controls are providedwhich operate each belt in response to a corresponding sensor and anoperative state of a downstream belt.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013]FIG. 1 is a diagramatic top view of a combined singulation andgapping system for an illustrative embodiment.

[0014]FIG. 2 is a control flow diagram for the infeed chute belt of theFIG. 1 embodiment.

[0015]FIG. 3 is a control flow diagram for the first belt of thesingulator section of the FIG. 1 embodiment.

[0016]FIG. 4 is a control flow diagram for the remaining belts of asingulator section of the FIG. 1 embodiment.

[0017]FIG. 5 is a control flow diagram for the first three belts of agapping section of the FIG. 1 embodiment.

[0018]FIG. 6 is a control flow diagram for the remaining belts of thegapping section of the FIG. 1 embodiment.

[0019]FIG. 7 is a timing diagram for the last six belts of the gappingsection of the FIG. 1 embodiment.

[0020]FIG. 8 is a timing diagram for all belts of the gapping section ofthe FIG. 1 embodiment illustrating minimum gap time logic.

[0021]FIG. 9 is a timing diagram for two of the belts of the gappingsection of the FIG. 1 embodiment illustrating clump eliminator logic.

[0022]FIG. 10 is a timing schedule for changing configurable timeperiods.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0023] Referring to FIG. 1, an illustrative apparatus in accordance withthe teachings of this invention is shown for randomly receiving articlesof variable size within selected limits in slugs having varying numbersof articles with varying orientations and for delivering the articlesone at a time with a controlled trailing-edge to leading-edge spacingbetween successive articles. Articles arrive and are singulated insection 40, proceed to section 42 where any remaining doubles areeliminated and large gaps between articles are reduced; and then proceedto section 44 where at least a minimum trailing-edge to leading-edgespacing between successive articles is established. Sections 42 and 44together comprise a gapping section and may also be referred to as agapping apparatus. From there, articles proceed to a sortation or otherappropriate stations for further manipulation or processing.

[0024] For the illustrative embodiment, articles arrive at singulationsection 40 from an infeed chute belt 60 through a large spiral slidechute 58. The singulation section is comprised of multiple belts 62 athrough 62 d, which are collectively referred to as surge belts 62because they carry forward some unsingulated slugs. Surge belts 62 areinterconnected by slide chutes 64 a-64 d, with slide chute 64 d leadingto section 42. Sensors 48 a-48 d are positioned so that there is atleast one sensor 48 x per each surge belt 62 x. Articles proceed fromthe infeed chute belt 60 onto the spiral slide chute 58, where they aresensed by photosensor 48 a, onto a surge belt 62 a, then through slidechute 64 a, and to a surge belt 62 b, and so on: from a surge belt 62 xto a slide chute 64 x to a downstream surge belt 62(x+1). Sensors 48 xare typically located at the ends of the corresponding surge belts 62 x.They are preferably placed at the belt elevation, looking across thebelt. There is belt guarding (not shown) on each side of each surge belt62 x in order to prevent articles from falling off, holes being formedin each guarding where sensors 48 are located. Sensors 48 are eachlocated within one quarter inch from a top of the corresponding belt 62because, in the environment of the illustrative embodiment, articles maybe as small as half an inch in one dimension—for example, music CDs,etc. Placing sensors 48 x at the ends of the corresponding belts 62 xmeans that they detect the articles as the articles are about to moveoff to the corresponding slide chute 64 x, which, combined with propercontrol settings, assists singulation while minimizing possible gapswithout closing them completely. Each belt is run by a motor controlledby control logic. For the illustrative embodiment, surge belts 62 arelocated at ninety degree angles to each other, and slide chutes 64separating them each have a different angle and slope, with eachsuccessive slide chute 64 being narrower than the previous one. Inaddition, surge belts 62 are inclined up, with slopes rangingapproximately from thirty to forty degrees, while the slide chutes areangled down at angles which may be steeper, but extend for a shorterdistance. These inclines are not required, but further assistsingulation. Surge belts 62 are wider and longer than belts at laterstages, but each belt 62 x is narrower than the preceding belt 62(x−1),so that articles are forced into a stream.

[0025] Infeed chute belt 60 and each of the surge belts is controlled bycontrols operating each belt 62 x in response to a corresponding sensor48 x and/or an operative state for a downstream surge belt. In apreferred embodiment, the surge belts 62 run at different speeds—eachbelt is faster than the belt preceding it, which further assistssingulation because faster downstream belts carry articles away andprevent clump creation. The controls can turn each surge belt 62 on oroff, depending on its current state, the state of at least onedownstream belt, whether the corresponding sensor is sensing anyarticles, and the throughput of the whole apparatus. That is, thearticles are singulated through selective, coordinated control of the onand off states for the belts. The infeed chute belt 60 is operated by acontrol subroutine shown in FIG. 2. The surge belt 62 a is operated by acontrol subroutine shown in FIG. 3, and the remaining surge belts 62b-62 d are operated by the control subroutines shown in FIG. 4.

[0026] Section 42 consists of a set of belts 66 e-66 g, which arecollectively referred to as buffer belts 66 because they carry mostlysingulated articles. Buffer belts 66 run at a faster speed than surgebelts 62 in singulation section 40 and function as high speed takeawaybelts. For an illustrative embodiment, belts 62 run at about 50-150 feetper minute, while belts 66 e-66 g run anywhere from 250 to 350 feet perminute. Each buffer belt 66 runs at a higher speed than the beltpreceding it.

[0027] An article arrives at section 42 from section 40 at a buffer belt66 e and leaves photosensor 48 e-48 g sensing articles at that belt.Each buffer belt 66 is operated by controls 76 according to a controlflow diagram (see FIG. 5), buffer belt 66 x being turned on or off inresponse to its current state, a corresponding sensor 48 x, the on/offstate of at least one downstream belt, for example belt 66(x+1) and, fora preferred embodiment, the throughput of the entire apparatus shown inFIG. 1.

[0028] Gapping section 44 consists of a set of belts 68 h-68 n, whichare buffer belts for an illustrative embodiment and are collectivelyreferred to as buffer belts 68. Buffer belts 68 run incrementally fasterthan each other, with speeds ranging from 200 to 500 feet per minute.Buffer belt 68 h runs slower than the buffer belt 66 g. Above each belt68 x there is a corresponding photosensor 48 x. Gapping is achievedthrough controls turning each buffer belt 68 x on or off according to acontrol subroutine (FIG. 6), each buffer belt 68 x being turned on/offin response to a corresponding sensor 48 x and/or the state of at leastone downstream belt, for example belt 68(x+1). Articles arrive at thegapping section 44 from section 42 at the buffer belt 68 h and leave theapparatus at a buffer belt 68 x, for example buffer belt 68 n for theembodiment of FIG. 1, from where they proceed to their next destination,for example a sortation station.

[0029] Additional fail-safes are available in the apparatus. Above surgebelts 62, buffer belts 66 and buffer belts 68, additional photosensors46 are located (shown for the surge belt 62 d; not shown, but presentabove other belts 62, 66 and 68). These photosensors are generally fordetection of jams that cannot be solved through cycling belts on and offand require human intervention. When articles exit at buffer belt 68 n,any remaining doubled articles, which should be minimal, if any, aredetected and re-routed back to the infeed chute 60 through a return path(not shown), so that they will go through the singulation process again.Belt controls 76 are implemented using a control computer capable ofconcurrently executing several subroutines, inputs to which are thestates of sensors and belts, as described below, and outputs from whichcontrol motors (not shown) for each of the belts in the apparatus. Thesubroutines may be implemented in any computer language, and may consistof additional subroutines.

[0030] Although the preferred embodiment uses a single computer toexecute all subroutines that comprise controls 76 in parallel,alternative embodiments may use a separate computer for each set ofsubroutines or bypass software and implement the subroutines in hardwareor hybrid circuits. A number of the subroutines at some point refer to aconfigurable time period, which is a variable setting, configuredaccording to a table in FIG. 10. An additional feedback loop (notshown)continuously monitors the apparatus output through athroughput-monitoring subroutine and, based upon a target throughput,adjusts variable time parameters to speed up or slow down the apparatusthrough changing the configurable time periods.

[0031]FIG. 2 is a flow diagram of an illustrative control subroutine foroperating the infeed chute belt 60 (FIG. 1) A default state for thissubroutine is state-80, system on, no faults, where the infeed belt isturned on and is running. When the system is in this state, thesubroutine monitors a photosensor 48 a and continuously runs a query 82to see if the photosensor 48 a has been blocked for more than aconfigurable time period 89 (FIG. 10). If an answer to this query isnegative, the system proceeds as previously, running the belt in step 85and returning to state 80. If, however, photosensor 48 a has beenblocked for a time greater than the configurable time 89, it means thatseveral articles are passing together, which is undesirable. In thatcase, the motor for the infeed belt is turned off (step 84) to delaytrailing articles, which are still on the infeed chute belt 60 and toallow articles which are already on the surge belt 62 a to proceed. Whenthe infeed chute belt is stopped, a query 86 is continuously run tocheck if the photosensor 48 a is still blocked (i.e. if articlesblocking the sensor have cleared). If the sensor is clear, thesubroutine returns to query 82 to determine whether to restart theinfeed chute belt 60. In this way, the control subroutine beginssingulation by separating the slug of articles into separate articles orsmall clumps of articles. The singulation process continues with controlsubroutines shown in FIGS. 3 and 4.

[0032]FIG. 3 is a flow diagram of a control subroutine for the surgebelt 62 a. A default state for this subroutine is state 90—system on, nofaults, where the surge belt 62 a is running. While the system is inthis state, a query 92 is continuously run to check if the downstreambelt—surge belt 62 b—is turned on. If the downstream belt is stopped, aquery 93 is run to check if a photosensor 48(a−1) is indicating anarticle at the beginning of the surge belt 62 b. If the photosensor48(a−1) is indicating an article and the downstream belt is not running,surge belt 62 a needs to be stopped (step 94) in order to avoid creatingmore doubles by bumping articles that are currently on the surge belt 62a into those that are currently on the surge belt 62 a. If, however,there are no articles at the beginning of the downstream belt, then itis safe to continue running surge belt 62 a (step 96) and system returnsto the default state 90.

[0033] If the query 92 indicates that downstream belt 62 b is running, aquery 95 is run to check if the photosensor 48(a−1) has been blocked fora period longer than a configurable time period 99 (FIG. 10). If theanswer is negative, belt 62 a continues to run (step 96) and systemreturns to default state 90. A positive answer to query 95 is a signthat an article double is coming through which needs to be singulated.In order to achieve singulation, surge belt 62 a is stopped (step 97) toallow surge belt 62 b to take away a front article of the double. Oncethe surge belt 62 a is stopped, a query 98 is continuously run to checkif the photosensor 48(a−1) has cleared. When photosensor 48(a−1)indicates that there are no articles present at the beginning of belt 62b, the system proceeds to run query 92 and repeats the steps thereafteras indicated above. This subroutine thus creates gaps between at leastsome consecutive articles by not running the belt 62 a when photosensor48(a−1) indicates that there are articles at the beginning of thedownstream belt, but running belt 62 a when this condition does notexist. This subroutine does not attempt to properly size or minimizesuch gaps, leaving that for the later stages 42 and 44.

[0034]FIG. 4 is a flow diagram of a control subroutine for operatingbelts 62 b, 62 c and 62 d. For each of those surge belts, referred to assurge belt 62 x, a separate instance of the subroutine is run. A defaultstate for this subroutine is state 100, where surge belt 62 x is runningand there are no faults. When the system is in state 100, a query 102 iscontinuously run to check if downstream surge belt 62(x+1) is running.If the answer query 102 is negative the downstream belt is not running aquery 103 is run to check if a photosensor 48 x is indicating presenceof an article. If no article is detected, the subrouting continuesrunning belt 62 x (step 104) and returns to the default state 100. If,however, an article is detected, belt 62 x is stopped (step 105) toavoid creating new doubles, and the subroutine returns to query 102. Ifthe answer to query 102 is positive (i.e. the downstream belt isrunning), a query 106 is run to check whether the photosensor 48 x hasbeen blocked for a period of time longer than a configurable time period107 (FIG. 10). A positive answer to the query 106 indicates that thereis still an article double, and surge belt 62 x is turned off for aconfigurable time period 109(FIG. 10) to facilitate separation of thedouble, and then turned back on, with the system returning to defaultstate 100. The fact that the downstream belt 62 x is running issufficient to assure that a gap is created during the stopping for theconfigurable time period 109. A negative answer to the query 106indicates that there is no double currently passing through belt 62 x,surge belt 62 x thus continuing to run (step 104) and the subroutinereturning to default state 100.

[0035]FIG. 5 is a diagram of control subroutine for controlling each ofthe buffer belts 66 e-66 g in the section 42. Belts 66 x are high speedtakeaway belts and the main goal for this section is to minimize gapsbetween the articles, so that the next section 44 can increase them tothe desired minimum size. For each of the buffer belts 66 x, a separateinstance of the subroutine is run. A default state for this subroutineis state 110—system on, no faults—where a belt 66 x is running. When thesubroutine is in this state, a query 112 is continuously run to check ifthe downstream belt 66(x+1) is running. If the downstream belt isrunning, there is no danger of creating additional doubles; thesubroutine therefore permits belt 66 x to continue running (step 113)and returns to default state 110.

[0036] If the downstream belt is not running, a query 114 is run tocheck if photosensor 48 x is indicating the presence of an article atthe end of the belt 66 x. If there is an article, buffer belt 66 x isstopped (step 115) and the subroutine returns to query 112. If there isno article present, the subroutine continues to run buffer belt 66 x(step 113), returning to the default state 110 despite the fact thatdownstream belt 66(x+1) is not running. This is done in order tominimize the gap between the articles; no additional doubles will becreated, because, by the time the next article moves to the end ofbuffer belt 66 x, either the downstream belt will be running, or bothqueries 112 and 114 will return negative results and belt 66 x will bestopped, avoiding combining two articles into a double.

[0037]FIG. 6 is a flow diagram of a control subroutine responsible foroperation of belts 68 in the section 44. The main goal for this sectionis to establish at least a minimum required gap between each pair ofsuccessive articles. In order to do that, gap time is increased to atleast minimum gap time in all cases where a detected gap is not longenough. A separate instance of the subroutine is run for each bufferbelt 68 x. A default state for this subroutine is state 120—system on,no faults, where belt 68 x is running. When the subroutine is in thatstate, a query 122 is continuously run to check if the trailing-edge toleading-edge gap for successive articles passing sensor 48 x is largerthan a required minimum gap 127 (see FIG. 7a). The check is madeaccording to the timing principles described later in conjunction withFIGS. 7-9. A negative answer to query 122 indicates that the detectedgap is not of sufficient duration, and buffer belt 68 x is stopped for atime period 129 described to be in conjunction with FIGS. 7-9 (step128). After the belt has been stopped for the time period 129, thesubroutine returns to query 122. However, if during the time period 129when buffer belt 68 x was stopped, downstream buffer belt 68(x+1) wasalso not running, the detected gap was not increased or increased by aninsufficient amount. The illustrative apparatus includes seven bufferbelts 68 running at different speeds, which increases the probabilitythat, if the detected gap is not sufficient, the downstream belt 68(x+1)will be running during the whole time period 129, thus creating at leastthe minimum required gap.

[0038] A positive answer to query 122 indicates that the detected gap isof sufficient duration. Query 123 is then made to determine ifdownstream belt 68(x+1) is running. If an answer is positive, there isno danger of decreasing the detected gap, and the subroutine proceeds torun belt 68 x (step 124), returning to default state 120. If, however,the downstream belt is not running, a query 125 is run to determine ifphotosensor 48 x indicates the presence of an article at the end of belt68 x. If there is no article present, the subroutine continues runningbuffer belt 68 x and returns to query 122, which monitors the detectedgap. If photosensor 48 x is not clear—the article is present—thesubroutine sends a stop signal to a motor for belt 68 x (step 126) andreturns to query 122, which ensures that the detected gap is not reducedbelow the minimum required gap.

[0039]FIGS. 7a and 7 b are timing diagrams that further illustratebehavior of queries 122 and 128 (FIG. 6). FIG. 7a shows how the existingtrailing-edge to leading-edge gap is detected. Sensor 48 x is “on” whenthere is no article passing, and “off” when there is an article at theend of the belt 68 x (FIG. 1). If the minimum gap time 127 is shorterthan detected gap time 131 and both belts 68 x and 68(x+1) are on, thenthe query 122 returns “yes”, the query 123 (FIG. 6) returns “yes” andbelt 68 x continues to run.

[0040]FIG. 7b illustrates behavior according to the control flow diagramof FIG. 6 when the detected gap time 131 is shorter than the minimumrequired gap time, as indicated by sensor 48 x. In that case, a “stop”signal is sent to belt 68 x in order to increase the gap. After acalculated period of time 132 (shown in FIG. 8), a “run” signal is sentto belt 68 x, restarting the belt.

[0041] When the “stop” signal is sent, belt 68 x does not stopimmediately—as every mechanical element, it has inertia and requiressome time to slow down and stop. Since the electronics are thus fasterthan the mechanical parts, the stop period needs to be lengthened totake this difference into account. A timing diagram for determination ofthe calculated time period 132 is shown in FIG. 8. If a differencebetween the detected gap time and the minimum required gap time is lessthan one third of the minimum required gap time, the calculated stopperiod is set to be one half of the minimum required gap time. This isdone in order to slow down the belts enough to create at least a minimumrequired gap. For example, if the minimum gap between trailing andleading of successive articles is T, and the detected gap is 4T/5, thecalculated stop period 132 is set to T/2. The appropriate times T arecalculated based on belt speeds, application, field-testing results,etc. If the difference between the detected gap time and the minimumrequired gap time is equal to or greater than one third of the minimumrequired gap time, the calculated stop time period is set to be thedifference between the detected gap time and the minimum gap time.

[0042]FIG. 9 illustrates timing logic employed in a subset of belts 68 x(in the illustrative embodiment this subset consists of belts 68 m and68 k) that facilitates eliminating doubles that were not eliminated inthe previous stages, where a double is a set of articles following soclosely one after another that there is no gap to detect. In order tocreate gaps between the articles in the doubles, additional “clumpeliminator” logic is employed. According to this timing logic, if sensor48 x is off for longer than a preset time period 134, belt 68 x isturned off for a configurable time period 133 in order to allow a frontarticle in the double to pass in order to create a gap. The preset timeperiod 134 is generally set to equal to or less than an approximate timeit would take for a largest article to pass (in the illustrativeembodiment, the length of the largest possible article is known).

[0043]FIG. 10 is an illustrative timing schedule for changing theconfigurable time periods discussed in conjunction with FIGS. 2, 3 and4. At any given time, all configurable time periods are set to be equalto the values in one of the columns of FIG. 10. For example, column 140b indicates that the configurable time period 89 for the infeed chutebelt 60 should be set to 1 second, a configurable time period 99 for thebelt 62 a should be set to 0.5 seconds, a configurable time period 107for the belt 62 b on-time should be set to 0.31 seconds, and aconfigurable time period 109 for the belt 62 b off-time should be set to0.57 seconds. When the throughput-monitoring subroutine indicates thatthe detected throughput differs from a desired throughput, theconfigurable time periods are adjusted by changing all values to thosein an adjacent column. When the detected throughput is greater than thetarget throughput, a left column is picked, and when the currentthroughput is less than the desired throughput, a right column ispicked. The configurable time periods are thus adjusted to target thedesired throughput. Although in the illustrative embodiment the timingschedule of FIG. 10 is used to determine the configurable time periods,depending on application and other factors, algorithms, different timingschedules or other techniques may be utilized to calculate configurabletime periods to achieve the desired throughput. In addition,configurable time periods may be adjusted based on feedback fromapparatus located after the apparatus of the FIG. 1 illustrativeembodiment. For example, the required minimum gap time period may bedynamically adjusted, based on selected factors both from the presentapparatus and from other apparatus used with it, such as size of thearticles, desired throughput, accuracy of processing at the downstreamstations, etc.

[0044] Although the illustrative embodiment of the invention has beenshown in the accompanying drawings and described in the DetailedDescription, it will be understood that the invention is not limited tothe embodiment disclosed. The number and kinds of belts employed, slidechute angles and sizes, as well as positioning of sensors and thecorresponding control subroutines can each be modified. The presentinvention is capable of rearrangements and modifications of parts andelements by one skilled in the art without departing from the spirit andscope of the invention, which is to be defined only by the appendedclaims.

What is claimed, is: 1) Apparatus for receiving articles in a slug andsingulating the articles, said apparatus including: a plurality of beltsmounted adjacent each other with a slide chute between each pair ofadjacent belts, articles being received on a first of said belts andpassing from one belt to an adjacent belt through the chutetherebetween; a plurality of sensors, positioned such that there is asingle control sensor for at least selected ones of said belts, eachcontrol sensor sensing article position relative to a correspondingbelt; and controls operating each belt in response to a correspondingcontrol sensor and an operative state for a downstream belt. 2) Theapparatus of claim 1, wherein each said control sensor is located at anend of a corresponding belt. 3) The apparatus of claim 2, wherein theend is an exit end of the corresponding belt. 4) The apparatus of claim1, wherein said controls are operative to initiate stopping of a belt ifa downstream belt is not running and a corresponding control sensor hasbeen blocked for a configurable period of time. 5) The apparatus ofclaim 4, wherein said controls are operative to start the belt when thedownstream belt is running. 6) The apparatus of claim 4, wherein saidconfigurable time period is such that said belt has not completelystopped when a run signal is sent. 7) The apparatus of claim 4, whereinsaid configurable time period is adjustable to achieve a desiredapparatus throughput. 8) The apparatus of claim 7, wherein saidconfigurable time period is adjustable according to an adjustmentschedule. 9) The apparatus of claim 1, wherein said controls include atleast one subroutine for each belt. 10) An apparatus for receivingarticles in a stream and creating a controlled gap between atrailing-edge of a leading article and a leading-edge of a successivearticle, said apparatus including: a plurality of belts mounted adjacenteach other, articles being received on a first of said belts and passingfrom one belt to an adjacent belt; a plurality of sensors, positionedsuch that there is a single control sensor for at least selected ones ofsaid belts, sensing article position relative to a corresponding belt;and controls operating each belt in response to a corresponding controlsensor and an operative state for a downstream belt; 11) The apparatusof claim 10, wherein said control sensor is located at an end of acorresponding belt. 12) The apparatus of claim 11, wherein the end is anexit end of the corresponding belt. 13) The apparatus of claim 10,wherein said plurality of belts are logically divided into a firstsection which minimizes a gap time and a second section whichestablishes at least a minimum gap time between successive articles. 14)The apparatus of claim 13, wherein the controls are operative toinitiate stopping of a belt in said first section if a downstream beltis not running and a corresponding control sensor is blocked and to senda run signal when the downstream belt is running again. 15) Theapparatus of claim 13, wherein the controls are operative to initiatestopping of a belt in said second section if a detected trailing-edge toleading-edge gap time at said belt is smaller than the minimum gap time.16) The apparatus of claim 15, wherein the controls are operative tosend a run signal to the belt stopped by the controls after a calculatedtime period. 17) The apparatus of claim 16, wherein the calculated timeperiod is a function of a difference between the detected gap time andthe minimum gap time. 18) The apparatus of claim 17, wherein thecontrols calculating said function include: (a) controls setting thecalculated time period to be equal to the difference between thedetected gap time and the minimum gap time if said difference is largerthan a determined fraction of the minimum gap time; and (b) controlssetting the calculated time period to be equal to a fraction of theminimum time period if the difference between the detected gap time andthe minimum gap time is less than a determined fraction of the minimumgap time. 19) The apparatus of claim 10, wherein said controls areoperative to initiate stopping of a belt in at least a subset of theplurality of belts if a corresponding control sensor has been blockedfor a predetermined time period. 20) The apparatus of claim 19, whereinsaid predetermined time period is adjusted to target a desiredthroughput. 21) The apparatus of claim 19, wherein said predeterminedtime period is less than or equal to a time it would take for a longestarticle to travel past the corresponding control sensor. 22) Theapparatus of claim 10, wherein said controls consist of at least onesubroutine for each belt. 23) In an apparatus for manipulating articlesof various size, said apparatus including stages of belts carrying saidarticles and belt controls for stopping and starting said belts, amethod for maintaining a desired article throughput, including the stepsof: (a) monitoring throughput for said article manipulation; and (b)controlling stop time intervals for at least selected ones of said beltsto maintain said desired throughput. 24) The method of claim 22, whereincontrolling stop time intervals in step (b) includes: (c) adjusting atleast selected said time intervals upward by a selected amount ifmonitored throughput is larger than said desired throughput; and (d)adjusting at least selected said stop time intervals downward byselected amounts if monitored throughput is smaller than the desiredthroughput. 25) The method of claim 24, wherein the adjusting of atleast selected stop time intervals in steps (c) and (d) includesadjusting the time intervals according to at least one adjustmentschedule. 26) The method of claim 25, wherein said adjustment scheduleis stored in a computer on which control subroutine are run. 27) Anapparatus for manipulating articles while maintaining a desiredthroughput, said apparatus including: stages of belts carrying saidarticles; controls operating each belt, said controls being operativefor stopping and starting said belts and including a subroutine formonitoring throughput for said article manipulation, and a subroutinefor controlling at least one of stop and run time intervals for at leastselected ones of said belts to maintain said desired throughput. 28) Theapparatus of claim 26, wherein said subroutine for controlling timeintervals includes: (a) a subroutine for adjusting at least selectedintervals upward by a selected amount if monitored throughput is largerthan the desired throughput; and (b) a subroutine for adjusting at leastselected intervals downward by a selected amount if monitored throughputis smaller than the desired throughput. 29) The apparatus of claim 27,wherein subroutines (a) and (b) adjust the at least selected intervalsaccording to an adjustment schedule. 30) Apparatus for receivingarticles in a slug, singulating the articles, and creating a controlledgap between a trailing edge of a leading article and a leading edge of asuccessive article, said apparatus including: a plurality of beltsmounted adjacent each other, articles being received on a first of saidbelts and passing from one belt to an adjacent belt; a plurality ofsensors, positioned such that there is a single control sensor for atleast selected ones of said belts, each control sensor sensing articleposition relative to a corresponding belt; and controls operating eachbelt in response to a corresponding control sensor and an operativestate for a downstream belt.